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EP0464118B1 - Traitement de metaux - Google Patents

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Publication number
EP0464118B1
EP0464118B1 EP90905565A EP90905565A EP0464118B1 EP 0464118 B1 EP0464118 B1 EP 0464118B1 EP 90905565 A EP90905565 A EP 90905565A EP 90905565 A EP90905565 A EP 90905565A EP 0464118 B1 EP0464118 B1 EP 0464118B1
Authority
EP
European Patent Office
Prior art keywords
superplastic
blank
combination
cold forming
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90905565A
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German (de)
English (en)
Other versions
EP0464118A1 (fr
Inventor
William Sinclair Courtstones Heath Road Miller
Roger Aston Hall Lodge Grimes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
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Filing date
Publication date
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Publication of EP0464118A1 publication Critical patent/EP0464118A1/fr
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Publication of EP0464118B1 publication Critical patent/EP0464118B1/fr
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/05—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/053—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/057—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S420/00—Alloys or metallic compositions
    • Y10S420/902—Superplastic

Definitions

  • This invention relates to the treatment of aluminium base alloys to enable superplastic deformation thereof to be achieved. It also includes a method of superplastically deforming such alloys.
  • the alloy should have a fine, stable, grain size (1 to 10 microns) or be capable of achieving such a grain size during hot deformation; be deformable at a temperature not less than 0.7 Tm (melting temperature) and at strain rates in the range 10 -2 to 10 -5 sec -1 .
  • Aluminium/lithium alloys such as 8090 and 8091 appear to possess many of the characteristics of the 2004 type in that they can be made to develop a fine grain structure by dynamic recrystallisation from an original grain structure not suitable for superplastic deformation. (see R. Grimes and W. S. Miller in "Aluminium-Lithium 2, Monterey CA 1984"). We have also shown, in UK Patent 2,139,536 how superplastic deformation of an Al/Li alloy can be achieved by modifying its high temperature deformation characteristics. (2) With alloys such as 7075 and 7475 that are subjected to a static recrystallisation treatment as their final stage in complex thermomechanical processing to develop a fine, stable, grain structure. Such alloys are then inherently capable of subsequent superplastic deformation.
  • Aluminium/lithium alloys are therefore unusual in that both processing routes can be applied to the same starting alloy chemistry to achieve superplasticity.
  • Work by Wadsworth et al has shown that good superplastic performance can be achieved by either process route.
  • Applicant's own European Patent Application published under Serial No. 0 104 774 A relates to a superplastic forming method in which a blank is cold worked so as to have a modified structure which upon a subsequent hot working step undergoes induced dynamic recrystallisation and superplastic deformation, the degree of modification of the crystal structure during the cold working step being such that as the dynamic recrystallisation continues the grain size is progressively refined.
  • this specification states all of (the alloys) require the use of a grain control constituent added primarily to enhance subsequent superplastic deformation and all require to be heavily cold worked before the superplastic deformation process.
  • a method of treating a blank of an aluminium base alloy in which a combination of heat treatments and cold forming operations are applied to the blank to produce a highly recovered semi-fabricated wrought product which is inherently non-superplastic and is capable of superplastic deformation only after an initial non-superplastic deformation to achieve dynamic recrystallisation wherein said combination comprises at least two said cold forming operations separated by an intermediate annealing step, and wherein said cold forming operations of said combination are such, and said heat treatments of said combination entail temperatures, heating rates and times such that application of said combination substantially avoids recrystallisation between the commencement of the first cold forming step and completion of the last cold forming step of the combination.
  • the said combination is preceded by the steps of holding the blank at a temperature between 275°C and 425°C for between 1 and 24 hours, and thereafter allowing the blank to cool to a temperature suitable for cold forming; and the said intermediate annealing step is effected by holding at a temperature of between 300°C and 400°C for no more than 2 hours using a first controlled heat-up rate of between 10°C and 200°C/hour and thereafter allowing the annealed product to cool.
  • the reduction ratio in each of the cold forming operations may be no greater than 25%.
  • the alloy may contain Zr as a grain controlling additive in a quantity no more than 0.3% and preferably less than 0.2%.
  • the product may be finally annealed at a temperature between 450°C and 500°C for no more than 2 hours using a second controlled heat-up rate of between 40°C and 200°C/hour, e.g. approximately 50°C/hour.
  • the highly recovered semi-fabricated product may be a cellular structure in which the cells are separated from one another by low angle boundaries and are contained within the grains.
  • the grains may be derived from a cast ingot from which the blank is derived, with their "as-cast" diameter in the range of 75 to 500 micrometers.
  • the alloy can be selected from alloys of Al/Cu/Mn/Mg; Al/Zn; Al/Li; Al/Mg; Al/Si/Mg; 2004 and its derivatives; 7075; 8090; 8091; 7010; and 7050.
  • samples were then all subjected to the same, known, high temperature deformation step.
  • the samples were pre-heated at 520°C for 10 minutes prior to deforming at a constant crosshead velocity (ccv) of 1.5 mm/min (an initial strain rate of 2x10 -3 /sec).
  • sample (a) (identical to Route 1) dynamic recrystallisation occured as it also did in sample (b). If an intermediate anneal is applied to the "known route 1 alloys" (i.e. 2004) there is a major drop in superplasticity, quite possibly to the point that the sheet is no longer superplastic.
  • the 8090 processed as example (b) behaved very differently from similarly treated 2004 in so far as the intermediate annealing treatment had virtually no effect upon the superplastic behaviour of the sheet.
  • the curve illustrated is a fair average of samples respectively deformed at cross head velocities of 12.5 mm/minute and 1.5 mm/minute (initial strain rates of 1.5x10 -3 /sec and 2x10 -3 /sec respectively).
  • Figure 1 shows that 350°C is an optimum temperature for 8090 to produce maximum subsequent superplastic deformation for material heat treated for 16 hours.
  • heat treatment temperatures between 275°C and 450°C produce reasonable superplasticity in the alloy.
  • the heat treatment process is a diffusion controlled phenomenon and is thus controlled by the conjoint effects of time and temperature.
  • time and temperature can be varied continuously to produce the necessary degree of microstructural change required to improve the material's subsequent superplastic performance.
  • Treatment at 350°C for 16 hours has been shown to be optimum for 8090 and produces similar results in 8091.
  • Other alloys may differ from this practice because of differences in their phase diagram and the diffusion rates of their solute elements.
  • Figures 2 and 3 show curves for alloys 8090 and 8091 treated as for samples (a) and (d).
  • the examples in Figure 2 were all preheated for 20 minutes at 525°C and tensile tested at a constant crosshead velocity of 3.4 mm/min (initial strain rate of 4.5x10 -3/ sec).
  • Figure 3 there was also a preheat step for 20 mins at 525°C.
  • the benefits of samples (d) are clearly apparant. Furthermore these samples are superplastic at a higher deformation temperature than samples (a) which is also advantageous.
  • blank heat treatment improves 8090's superplastic performance by a factor of 2 1/2 to 2.
  • the improvement in superplastic ductility increases with increasing test temperature.
  • the improvement in superplasticity with blank heat treatment is small below 500°C,but is significant above 500°C, i.e. within the solution treatment temperature range of the alloy.
  • Figure 3 shows that when tested at the alloy's solution treatment temperature (525°C) the improvement in superplasticity with blank heat treatment is maintained over a wide range of crosshead velocities for both alloys.
  • Sample 5 has the lowest overall superplastic capability. Thus solution treating prior to lower temperature heat treatment is not preferred.
  • Sample 3 has the better superplastic capability particularly at the higher strain rates and higher test temperatures.
  • Figure 4 shows the cavitation observed in optimised route material compared to that found in the same alloy processed using Route 1 above.
  • Figs 5, 5A; 6, 6A; 7, 7A and 8, 8A compare the grain structure observed during superplastic forming of optimised route material compared to material processed via route 1.
  • the optimised route material develops a fine grain structure (necessary for good superplastic performance and low flow stress) at a much earlier stage of straining.
  • optimised route 8090 material of the above summary shows a flow stress of 5.3 MPa (L-direction) 4.8 MPa (T-direction)
  • Alloy 2004 is normally produced using the method of Route 1 above and good superplastic behaviour results.
  • Figures 9 and 10 show that alloy 2004 can be processed with advantage in accordance with the present invention. This improves the superplastic forming properties and increases the optimum forming temperature thus allowing easier control of cavitation during superplastic forming.
  • the cold rolling operation can also be rendered easier by use of the present invention.
  • the final annealing step generally has little effect because a very efficient grain controlling dispersion of ZrAl 3 particles is normally present in the alloy.
  • the essential feature is to develop via the processing a highly recovered wrought product but to avoid static recrystallisation.
  • This highly recovered structure leads to improved superplastic elongations, reduced tendency for the alloy to cavitate during deformation and a lower flow stress. All these features are desirable requirements for an alloy that is to be superplastically deformed.
  • the present invention provides a superplastic forming route for Al base alloys in which the starting material is subjected to heating rates at such temperatures and for such times and to such cold forming operations that static recrystallisation is substantially avoided both during annealing and during pre-heat for superplastic forming. More specifically we have found the following parameters suitable:-
  • the sheet has been tested under uni-axial tension whilst subjected to a hydrostatic pressure of 650 psi. At 485°C using a strain rate of 1 x 10 -3 s -1 an elongation to failure of 400% was obtained. The flow stresses have been measured as a function of strain rate, and from this the superplasticity index, m, obtained. These values are shown in Table 1.
  • the highly recovered semi-fabricated wrought product of the present invention may be a cellular dislocation structure with a cell diameter of approximately 10 micrometers.
  • the cells are separated from one another by low angle boundaries and are contained within the grains. These grains may have been derived from the cast ingot from which the blank is derived and their "as cast" diameter is preferably in the range of 75 to 500 micrometers.

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  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Forging (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Glass Compositions (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)

Claims (11)

  1. Procédé de traitement d'une ébauche constituée d'un alliage à base d'aluminium dans lequel une combinaison de traitements thermiques et d'opérations de formage à froid est appliquée à l'ébauche pour produire un produit travaillé semi-fini fortement revêtu qui de manière inhérente est non-superplastique et est capable de subir une déformation superplastique uniquement après une déformation initiale non-superplastique pour aboutir à une recristallisation dynamique, dans lequel ladite combinaison comporte au moins deux opérations de formage à froid séparées par une étape de recuit intermédiaire, et dans lequel lesdites opérations de formage à froid de ladite combinaison sont telles, et lesdits traitements thermiques de ladite combinaison sont tels qu'ils entraînent des températures, des vitesses de chauffage et des temps de chauffage tels que l'application de ladite combinaison empêche pratiquement une recristallisation entre le début de la première étape de formage à froid et la fin de la dernière étape de formage à froid de la combinaison.
  2. Procédé selon la revendication 1, dans lequel ladite combinaison est précédée par les étapes consistant à maintenir l'ébauche à une température située entre 275°C et 425°C pendant entre 1 et 24 heures, et à permettre après ceci à l'ébauche de refroidir jusqu'à une température adaptée pour le formage à froid, et dans lequel ladite étape de recuit intermédiaire est effectuée en maintenant une température comprise entre 300°C et 400°C pendant pas plus de 2 heures en utilisant une première vitesse de chauffage commandée située entre 10°C et 200°C par heure et après ceci en laissant refroidir le produit recuit.
  3. Procédé selon la revendication 1 ou 2, dans lequel le rapport de réduction de chacune desdites opérations de formage à froid n'est pas supérieur à 25 %.
  4. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'alliage contient du Zr en tant qu'additif de commande de grain, selon une quantité qui n'est pas supérieure à 0,3 %.
  5. Procédé selon la revendication 4, dans lequel la quantité est inférieure à 0,2 %.
  6. Procédé selon l'une quelconque des revendications précédentes, dans lequel le produit est finalement recuit à une température comprise entre 450°C et 500°C pendant au maximum 2 heures en utilisant une seconde vitesse de chauffage commandée située entre 40°C et 200°C /heure.
  7. Procédé selon la revendication 6, dans lequel la seconde vitesse est d'approximativement 50°C/heure.
  8. Procédé selon l'une quelconque des revendications précédentes, dans lequel le produit semi-fini fortement revêtu est une structure cellulaire dans laquelle les cellules sont séparées les unes des autres par des limites faiblement inclinées et sont contenues à l'intérieur des grains.
  9. Procédé selon la revendication 8, dans lequel les grains sont dérivés d'un lingot coulé à partir duquel l'ébauche est dérivée et leur diamètre "venu de coulage" est dans la plage allant de 75 à 500 micromètres.
  10. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'alliage est choisi parmi les alliages de Al/Cu/Mn/Mg; Al/Zn; Al/Li ; Al/Mg et Al/Si/Mg.
  11. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'alliage est choisi parmi 2004 et ses dérivés; 7075; 8090, 8091; 7010; et 7050.
EP90905565A 1989-03-21 1990-03-20 Traitement de metaux Expired - Lifetime EP0464118B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB898906468A GB8906468D0 (en) 1989-03-21 1989-03-21 Metal treatment
GB8906468 1989-03-21
PCT/GB1990/000429 WO1990011385A1 (fr) 1989-03-21 1990-03-20 Traitement de metaux

Publications (2)

Publication Number Publication Date
EP0464118A1 EP0464118A1 (fr) 1992-01-08
EP0464118B1 true EP0464118B1 (fr) 1997-08-20

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EP90905565A Expired - Lifetime EP0464118B1 (fr) 1989-03-21 1990-03-20 Traitement de metaux

Country Status (8)

Country Link
US (1) US5490885A (fr)
EP (1) EP0464118B1 (fr)
JP (1) JPH04504141A (fr)
AT (1) ATE157128T1 (fr)
AU (1) AU640641B2 (fr)
DE (1) DE69031307T2 (fr)
GB (1) GB8906468D0 (fr)
WO (1) WO1990011385A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH682081A5 (fr) * 1990-11-12 1993-07-15 Alusuisse Lonza Services Ag
JPH07145441A (ja) * 1993-01-27 1995-06-06 Toyota Motor Corp 超塑性アルミニウム合金およびその製造方法
JP5354954B2 (ja) 2007-06-11 2013-11-27 住友軽金属工業株式会社 プレス成形用アルミニウム合金板
RU2618593C1 (ru) * 2015-11-19 2017-05-04 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Уфимский государственный авиационный технический университет" Способ термомеханической обработки полуфабрикатов из алюминиевых сплавов систем Al-Cu, Al-Cu-Mg и Al-Cu-Mn-Mg для получения изделий с повышенной прочностью и приемлемой пластичностью

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4021271A (en) * 1975-07-07 1977-05-03 Kaiser Aluminum & Chemical Corporation Ultrafine grain Al-Mg alloy product
JPS5822363A (ja) * 1981-07-30 1983-02-09 Mitsubishi Keikinzoku Kogyo Kk 超塑性アルミニウム合金板の製造方法
CA1198656A (fr) * 1982-08-27 1985-12-31 Roger Grimes Alliages metalliques legers
US4486242A (en) * 1983-03-28 1984-12-04 Reynolds Metals Company Method for producing superplastic aluminum alloys
CH654027A5 (de) * 1983-08-23 1986-01-31 Alusuisse Verfahren zur herstellung feinkoerniger aluminiumwalzprodukte.
US4618382A (en) * 1983-10-17 1986-10-21 Kabushiki Kaisha Kobe Seiko Sho Superplastic aluminium alloy sheets

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
"Introduction to Dislocations", D. Hull, Oxford 1965, pages 192-205 *
3rd International SAMPE Metals Conference, Oct.20-22, 1992, pages M192-M206 *
Journal of Applied Physics, 46 (11), 1975, pages 4951-4956 *
Journal of Crystal Growth 8 (1971) pages 235-242 *
Materials Science and Technology, June 1991, vol. 7, pages 544-553 *
Proceedings of Conf. "Deformation of Multiphase and Particle Containing Materials", Riso 1983, pages 243-250 *

Also Published As

Publication number Publication date
JPH04504141A (ja) 1992-07-23
AU5346090A (en) 1990-10-22
US5490885A (en) 1996-02-13
DE69031307D1 (de) 1997-09-25
ATE157128T1 (de) 1997-09-15
DE69031307T2 (de) 1998-03-26
WO1990011385A1 (fr) 1990-10-04
GB8906468D0 (en) 1989-05-04
AU640641B2 (en) 1993-09-02
EP0464118A1 (fr) 1992-01-08

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